Catching runtime errors in Javascript - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to catch errors using try-catch.

Javascript

try {
  console.log('Start');
  [1]
} catch (error) {
  console.log('Error caught');
}

Drag options to blanks, or click blank then click option'

Aconsole.log('No error')

Blet x = 5

Cthrow new Error('Oops!')

Dreturn true

Attempts:

3 left

💡 Hint

Common Mistakes

Not using throw causes no error to catch.

Using return inside try without error does not trigger catch.

The throw statement inside try causes an error that is caught by catch.

2fill in blank

medium

Complete the code to log the error message inside catch.

Javascript

try {
  JSON.parse('invalid json');
} catch ([1]) {
  console.log([1].message);
}

Drag options to blanks, or click blank then click option'

Aerror

Be

Cerr

Dexception

Attempts:

3 left

💡 Hint

Common Mistakes

Using different names inside catch and inside the block causes ReferenceError.

Omitting the catch parameter causes syntax error.

The catch block parameter is commonly named error to access the error object.

3fill in blank

hard

Fix the error in the code to properly catch exceptions.

Javascript

try {
  let result = a / 0;
  console.log(result);
} catch [1] {
  console.log('Error:', error.message);
}

Drag options to blanks, or click blank then click option'

A(error)

B[error]

C{error}

Derror

Attempts:

3 left

💡 Hint

Common Mistakes

Using brackets or braces instead of parentheses causes syntax error.

Omitting parentheses causes syntax error.

The catch block must have parentheses around the error parameter.

4fill in blank

hard

Fill both blanks to throw and catch a custom error message.

Javascript

try {
  [1] new Error('Custom error');
} catch (e) {
  console.log(e.[2]);
}

Drag options to blanks, or click blank then click option'

Athrow

Bmessage

Cname

Derror

Attempts:

3 left

💡 Hint

Common Mistakes

Using error instead of throw does not raise an error.

Accessing e.name instead of e.message shows error type, not message.

Use throw to raise the error and access e.message to get the error text.

5fill in blank

hard

Fill all three blanks to parse JSON safely and handle errors.

Javascript

function safeParse(json) {
  try {
    return JSON.[1](json);
  } catch ([2]) {
    console.log('Parsing failed:', [3].message);
    return null;
  }
}

Drag options to blanks, or click blank then click option'

Aparse

Berror

Ce

Derr

Attempts:

3 left

💡 Hint

Common Mistakes

Using JSON.stringify instead of parse causes wrong output.

Mismatch between catch parameter and usage causes ReferenceError.

Use JSON.parse to parse, catch parameter e, and log e.message.